The Hawaiian Electric Companies are offering an optional Time-of-Use rate program that will charge customers less for power used during the day – when solar energy production is highest – and more at night.

Developed under the direction of the Hawaii Public Utilities Commission, these rates encourage customers to use electricity when solar power is abundant and enable cost-effective integration of renewable energy.

This program will provide customers with an opportunity to save money if they shift their energy use to daytime hours. For example, customers who do laundry, cook, or heat water during the day may be able to save. Customers who charge electric vehicles or energy storage systems in the day may also benefit. The amount of any savings will depend on how much a customer changes their usage. As a result, this program may not fit the needs of all customers.

Here’s how the rates will compare with current residential rates for October 2016 (all prices in cents per kilowatt-hour):

As directed by the PUC, this program will run for two years and these rates are only for residential customers. Participation will be voluntary and limited to the first 5,000 customers who enroll.

Participating customers will receive information on their bills that compares their costs under this program and the normal residential rate for electricity. Customers may opt out of the program at any time if they feel it isn’t the right fit for them.